A test program was undertaken by the Mine Safety and Health Administration (MSHA) to determine the feasibility of coating polystyrene block walls for fire protection. Selected coatings, used in the mining industry, were tested under semilarge scale, simulated mine fire conditions to determine the appropriate thicknesses of these coatings for protection of the polystyrene foam block against fire for specified expanded vermicultie, portland cement, and limestone coating were particularly effective in protecting the foam blocks against the heat of simulated mine fire.